Road tunnels



l 'auf June 30, 1959 Filed May 20. 1953 F. CENA 2,892,418

ROAD TUNNELS 5 Sheets-Shea?I 1 13' off/wf- June 3o, 1959v F. cl-:NA

ROAD TuNNELs Filed llay 20. 1953 5 Sheets-Sheet 2 3/ A l Q.. v4 :a gli3. n@

June 30, 1959 F. CENA 2,892,418

R/OAD TUNNELS l Filed May 2,0'. 1955 l 5 Sheets-Sheet. 3

y June 3o, 1959 F. CENA l 2,892,418

ROAD TUNNELS Filed May 2o. 195s 5 sheets-sheet 4 EVN r92 rss rm r 9B 96I 166 O O O C) O June 30, 1959 F.l CENA 2,892,418

ROAD TUNNELS Filed May 20. 1953 5 Sheets-Sheet 5 United y States PatentO ROAD TUNNELS Ferdinando Cena, Turin, Italy Application May 20, 1953,Serial No. 356,136 Claims priority, application Italy January 17, 1953 4claims. (ci. 104-172) Y This invention relates to improvements in roadtunnels. It is known that all road tunnels exceeding in length a certainlimit, should be artificially ventilated. This limit can vary inaccordance with t-he tunnel profile and section, importance of traffic,climate and weather conditions, prevailing wind, etc. v

Broadly, it may be assumed that natural ventilation without the use ofspecial Ventilating plants should be limited to tunnels not exceeding600-700 meters in length. When the intensity of traffic ranges withinmoderate limits, and weather conditions are exceptionally favourable tonatural air circulation in the tunnel, tunnel lengths up to about 3kilometers may be reached without the vneed for forced ventilation ofthe tunnel.

However, wit-h a great traic, even in the last-mentioned cases, thecarbon monoxide concentration in the air filling the tunnel rapidlyincreases, often with a considerable reduction in visibility owing tosmoky exhaust from the engines of motor vehicles travelling through thetunnel.

Consequently, any road tunnel of a certain importance should in the endbe provided with a forced ventilation plant. Now, the cost of such plantaudits upkeep is very high and appreciably affects the `cost ofinstallation and service.

It has, however, been found that any type forced ventilation plant forroad tunnels is insufficient for totally eliminating the danger ofpollution Ifrom toxic stuffs from the inside of the tunnel and reductionin visibility therethrough when the traic through the `tunnel reaches agiven intensity, which necessitates holding up traffic during more Vorless long periods of time,` at any rate till the air within the galleryhas been sufliciently purified to admit'of resuming traffic. Y

This invention provides road tunnels with means adapted to eliminateforced draught plants or to considerl ably reduce them in capacity,thereby cutting down cost of installation upkeep and service.

A road tunnel according to this inventionis provided with meanspermitting travel therethrough of vehicles with their engines in aninoperative condition, the vehicle weight resting on the vehicle wheelswithout loading the vehicle on carriages, platforms or similartransporting means.

With this object in view, a motor vehicle convoy is formed at the inletofthe tunnel, the vehicles being connected together through suitablemeans to a suitableV propelling means, such as an electric locomotive orendless rope or belt conveyor which pulls them with theirA engines in aninoperative condition through the tunnel to the outlet thereof where thevehicles are released from the trailer or propelling means and areallowed 'to run on their engines again. v

It is 4understood that when endless rope or belt conveyors are used,they should be operated by driving means of such type and in sucharrangement as not to pollute the air in the tunnel during operation.

z For a safer propelling of a convoy comprising vehicles fcc connectedto a trailing means and in order toV avoid traction of the individualvehicles attached in line to one another according to this invention,each vehicle is secured to a carriage slidable on rails preferablyarranged in a small auxiliary tunnel situated beneath the road surfaces,and extending throughout the length of the tunnel. These carriages canbe connected together by suitable couplings and to trailing means, suchas au electric locomotive or an endless rope or belt conveyor extendingthroughout the length of the tunnel or part thereof. v

The vehicle is secured to the carriage through suitable means providedwith hooks, such as ropes, draw-bars or push-bars provided with membersfor engaging the motor vehicles projecting above the road surface fromthe auxiliiary tunnel through a narrow longitudinal slot symmetricallysituated with respect to the plane of symmetry of the road surface ofthe actual or main tunnel.

The attachment of the vehicles and individual carriages as well as thearrangement of the electric locomotive according to this invention canbe such that the unit forming the vehicle train to be conveyed throughthe tunnel can all be pushed or drawn during its movement.

According to this invention the use of the above described carriagesdoes not necessarily imply building an auxiliary tunnel underneath theroad surface. The carriages c an run on guide or rails arranged in anysuitable manner in the tunnel, for instance in proximity of the roof. A

The invention is more particularly advantageous in sloping tunnels inwhich the translational movement of the vehicles secured to theabovementioned carriages with their engines in an inoperative conditionpartly takes place by gravity by virtue of the weight of the vehiclesand carriages, thereby assisting the electric locomotive which actionmay be limited to a controlling and braking function, in order to vavoidexceeding a determined safety speed of the convoy. In an opposite uphilldirection, the electric locomotive or suitably trailing or pushing meansof another type propel the convoy. Tunnels of this type afford highly[favourable natural conditions for ventilation.

v According to this invention the plant of the ytype referred to abovecan be combined with a tunnel of a special type, Idesigned, if localconditions permit, to include -two runs opposite in slope, eachcomprising successive por-l tions of gradually decreasing inclinationfrom the inlet athigher level -towards the outlet lower level of thetunnel of each run.

It is then possible -to propel the convoy at high speed from the inletof the tunnel and gnadually decrease its speed towards the outlet. Inthis case also motor-ve hicles with their engines in an inoperativecondition travel through the gallery substantially under the action oftheir own weight and the battery of carriages connected to a propellingmeans `or an electric locomotive is more particularly intended to act assafety devices for adjusting both the spacing between the vehiclesdepending upon the spacing of the carriages, and the speed through theeffect of the braking action exerted by the electric locomotive orpropelling means.

Itis understood that the vehicles could in this ease be started withtheir engines of without attaching them in any manner, adjustment oftheir speed of transit through the tunnel being effected merely by thelength and slope of the individual sections of the down-hill run of thetunnel.

j connections.

'Further features and objects of this invention will be more clearlyunderstood from the appended description referring to the drawings,wherein:

Figure l is a longitudinal section of a tunnel portion according to thisinvention,

Figure 2 is a sectional view of a section of a modified tunnel accordingto this invention,

Figure 3 is a side view of a carriage,

Figure 4 is a section on line IV-IV of Figure 3,

Figure 5 is a side view of a constructional detail of the carriage,

Figure 6 is a plan view, of the carriage shown in Fig. 5,

Figure 7 is a part sectional side view of a constructional detail ofthecarriage according to a modification,

Figure 8 is a section on line VIIl-VIII 0f Figure 7,

Figure 9 is a side view of a carriage according to an othermodification,

Figure 10 is a section on line X--X of Figure 9,

Figure 1l is a sectional view of a portion of a road tunnel providedwith an endless rope conveyor,

Figure 12 is a sectional view on line XII- XII of Figure ll,

Figure 13 is a view of a constructional detail of the endless ropeconveyor on an enlarged scale.

Figure 14 isa section on line XIV- XIV of Figure 13 on a furtherenlarged scale,

Figure 15 is a diagrammatic sectional view of a tunnel with downwardlydirected slope,

Figure 16 is a diagrammatic sectional view of a con structioual detailof a tunnel shown in Fig. ll,

Figure 17 is cross sectional view of a railway tunnel converted to aroad tunnel equipped according to this invention,

Figure 18 is a cross sectional view of a similar tunnel according to amodification.

Referring to Figure l, 1 denotes the vehicles conveyed through the roadtunnel 2 with their engines in an inoperative condition, their weightbearing on their respective wheels rolling on the road surface 3 in thetunnel. The rear axle of each motor vehicle is secured to a carriage 4running onv rails 5 arranged in an auxiliary tunnel 6 beneath the roadsurface 3 in the tunnel 2.

The carriages 4 are connected together by means of spacing bars 7, `thelforemost carriage being connected with the electric locomotive 8 bymeans of a bar 9.

The electric locomotive 8 is operated by the electric current derived bymeans of a trolley 10 from the overhead conductor 11 hung to the tunnelroof 12, and is provided with reserve storage batteries to ensurefurther operation on accidental failure of current.

The construction shown in Figure 2 differs from Figure l in that thecarriages having secured thereto the vehicles conveyed through thetunnel with their engines in an inoperative condition, are translated bymeans of endless band conveyors 13, 14, instead of by an electriclocomotive. The conveyor bands 15, 16 are formed with projections 17 atright angles to the band surfaces which during motion of the conveyorsengage suitable abutments on the carriages 4.

The vehicles are conveyed one by one through the tunnel, withoutconnecting together the carriages to which the vehicles are attached.

By employing the endless bands a variable feed rate launching band isarranged at the inlet of the tunnel. This band of reduced length isintended to accelerate the vehicles secured to the carriages at a speedsubstantially equalling the feed rate of the band conveying the vehiclethrough the tunnel. As, for example, the conveyor 15 in Fig. 2 can bedriven at a progressively increasing speed after projections 17 engagean individual carriage 4 and thereby accelerate the carriage to aselected speed. The carriage is then automatically transferred toconveyor 16 which moves it and the vehicle throughout the length of thetunnel at said selected speed through.-

4 out the full length of the tunnel to the exit thereof. It willV beunderstood that rather than using a sole constant speed conveyor such asconveyor 16 a plurality of constant speed conveyors may be employed withthe individual carriages and towed vehicles being autovmaticallytransferred from conveyor to conveyor.

Figures 3 to 9 show some types of the carriages to which the vehicles tobe conveyed through the tunnel are attached, as well as constructionaldetails.

The carriage construction shown in Figure 3 and 4 is substantiallysimilar to the construction diagrammatically shown in Figures l and 2.

The carriage shown in Figures 3 and 4 comprises a frame 18 carried byfour upper wheels 19 running on the rails 5 carried by the cross members20 anchored to the side walls 21 of the auxiliary gallery 6. A pair oflower wheels 22 engage below the rails 5 and prevent any sticking of thecarriage.

As mentioned above, the carriages are connected together by spacingdraw-bars 7 connected thereto through the interposition of cardan joints23 to assist the carriages in going over from one tunnel portion toanother portion differing in slope.

The frame 18 has attached to opposite ends hooks 24 reaching slightlyabove the road surface 3 through a central slot 25 connecting the roadtunnel 2 with the auxiliary tunnel 6.

Each hook 24 is connected to the frame 18 through the interposition of aspring 26 in order to be capable of a slight displacement in a verticaldirection.

The hooks 24 can have attached thereto a rope 27 provided with a shockdamper 28 and two jaws 29 adapted to clamp, for instance, the rear axlehousing portions'actuated on both sides of the diierential casing of thevehicle, said jaws being anchored to the carriage and connected to itheshock damper over a cross member 30.

The rope 27 can be made a shorter or longer and since this rope iscapable of oscillation in a vertical and a horizontal plane, the jaws 29can be easily suited to the axle of a vehicle of any height andtransverse displacement of the trailed vehicle during feed cannot injurethe attachment means.

The attachment means for fastening motor vehicles to the carriages shownin Figures 3 and 4 are arranged to draw the motor vehicle axle connectedthereto during their movement through the tunnel.

Figs. 5 and 6 show a modified structure of the means for connecting thecarriage to the vehicle to be conveyed. Each end of the cross rod 30 hassecured thereto a clamping device formed by a pair of lower jaws 31keyed to the ends of a cross shaft 32 rotatably supported by the crossrod 30 and carrying at half-length a lever 33 hinged at one end to thecore of an electromagnet 35, the upper jaws 36 of the clamping devicearranged on either side of the bar 30 being iixedly connected to thecross member 30. A spring 7 fastened between the shock absorber casing28 and the end of lever 33 remote from the core of the electromagnettends to maintain the clamping device 31, 36 in its opened position.Current ows to the electromagnet through a cable 38 which is preferablyconnected by a longitudinal conductor formed by portions interconnectedby plugs and socket members extending throughout the carriages andconnected to the electric locomotive for controlling from the driverscabin engagement and disengagement of the clamping devices 31 and 36 ofthe motor vehicle axles with respect to the electric locomotive byconnecting and disconnecting by means of a switch Ithe currentenergising the electromagnets 35.

In the example shown, during transit through the tunnel all theelectromagnets are fed by the current and hold the clamping devices 31,36 closed. 0n reaching the tunnel outlet, the engineer on the electriclocomotive cuts out the current automatically and all the clampingdevices 31, 36 open under the action of their respective springs 37.

Figures 7 and 8 show a modified fastening, comprising a hook 39connected over'a shock absorber 28 to a helically wound band spring 40connected by its inner end to the carriage frame 18.

This arrangement is advantageous inasmuch as the fastening hookstogether with their shock absorber are automatically withdrawn by theaction of the helical spring 40 into the slot 25 in the road surface,from which they do not project when they are released from the vehicles.Figures 9 and 10 show a modified carriage construction, comprising a topwheel 41 rolling on the upper surface of a rail 42, which is, forinstance, anchored below Ain the oor of the auxiliary tunnel 6, providedwith four rollers 43 with a vertical axis adjacent to the sides of therail web and holding the carriage ina vertical position. The connectionbetween the carriages as well as the means for attaching the vehiclesthereto do not differ appreciably from those described above.

An embodiment of the invention employing an endless rope conveyor isshown in Figures l1 to 14.

Referringto Figures 1l `and 12, the tunnel 70, of a size suitable formeeting the requirements of traic in both directions has arrangedtherein in proximity to the roof an endless rope driven at a constantspeed by a driving or transmission wheel rotated by suitable means, forinstance from an electric motor (not shown). The rope is arranged insuch manner that its two runs 72 and 73 parallel with each other andarranged at the same height are carried by bearings 74 provided withrollers 75 and anchored in the tunnel roof. The direction of movement ofeach run (indicated on the drawing by the arrows) of the rope isopposite to the direction of movement of the other run. Carriages 76 arefastened to the rope by means of suitable vices, each carriage havinghinged to its lower portion a ring 77 to which is fastened the hook 78secured to the upper end of a rope, of which the lower end is securedthrough the interposition of a shock absorber 79 to the frame of aVehicle 80. The spacingof the two runs 72, 73, respectively of the ropeisA such as to admit of travel through the tunnel of vehicles inopposite directions, each vehicle being drawn by a carriage secured toits respective rope run.

.The above described arrangement would be impractical if the carriageswere constantly attached to the rope which necessarily moves athighspeed. In fact, it would be extremely diflicult, if not impossible,to disconnect the trailed vehicle reaching the outlet end of the tunneland to connect the vehicle at the inlet end.

In order to avoid this drawback, the invention provides an arrangementsubstantially known per se in other fields, which permits ofdisconnecting the rope and stopping the carriage as it reaches thetunnel end, its stoppage toV wait fora vehicle to be conveyed throughthe tunnel, and` its acceleration and subsequent connection to the roperun opposite that which has reached the tunnel outlet.

With this object in view, the carriage frame, which is substantially inthe form of a vertical plate 81 (Figures 13 and 14) is provided with avice which clamps and releases the conveyor rope 72, respectively. Thisvice comprises a stationary member 82 and a movable member 83 in theform of a lever rotating about the shaft 84 fixed to the frame 81. Thespring 85 tends to maintain the vice constantly in its open position, inwhich the members81 and 82 do not engage the rope 72.

The end 83a of the member 83 contact an eccentric 86 keyed to the pivot87 rotatably mounted on the carriage frame 81.

Al laterally projecting lever 88 is fixedly connected to the pivot 87. v

Two rails or guides 89, 90, respectively (Figures 13 and 14) aresuspended near the region at which the conveyor rope travels over thedriving or transmission wheel 71 on either side thereof, said rails o rguides being jarranged in a vertical plane extending through theassociated rope run, over and beneath the rope, respectively.

A set of rollers 91 95 and 91 95 (Fig. 12) are aligned over each of thetop rails 89, said rollers being mounted in a frame 96 anchored to thetunnel roof which further carries the rails 89 and 90. The rollers areconstantly rotated by a motor, such as an electric motor through a drive(not shown) such that the successive rollers'rotate at a speed such thattheir peripheral speed gradually decreases from the roller 91, 91',respectively, of which the peripheral speed nears the feed rate of theconveyor rope. The peripheral speed of the roller 95 and 95',respectively is very low, near zero.

Assuming the rollers above the run 72 of the rope rotate in thedirection denoted by the arrows in Figure 13, the rollers over the side73 rotate at equal peripheral speeds butin opposite directions.

The mechanism described operates as follows.

When the carriage 76 trailing the vehicle 80, anchored to the run 72 ofthe rope reaches the end of the rails 89 and 90, the latter engage therollers 97, 98, respectively (Figures 13, 14). At the same time the endof lever 88 is engaged by stationary guide 99 which moves it from itslowered position, in which the vice is closed, by the action of theeccentric 86 to the raised position shown in Figure 14, in which thecarriage 76 is disconnected from the run 72 of the rope. At the sametime the shoe fast with the carriage frame 81 successively comes intocontact with the rollers 91 95 and the carriage speed is reduced nearlyto nil by the effect of the friction between the upper surface of theshoe and the rollers 91 to 95. The vehicle can then be released andleaves the tunnel outlet by self-propulsion, as the carriage is moved byhand by pulling the rope on to the rail 101 connecting the rails 89together (Fig. 12).

When a vehicle comes in front of the tunnel inlet, it is fastened to thecarriage carried by the rails 101, the carriage being drawn by hand inthe direction of movevment of the run 73 of the conveyor rope till theshoe by a guide similar to the guide 99 which lowers the leverA 88,thereby fastening the carriage to the run 73 of the conveyor rope.A Thecarriage is thus moved to the opposite end of the tunnel carrying alongthe vehicle.

It is understood that the plant has been described and illustrated in adiagrammatic manner for the purpose of explanation and can undergovarious modiiicatoins without departing from the scope of thisinvention.

Figure l5 shows diagrammatically a preferred embodiment of a slopingroad tunnel, with which the above described arrangement can be usefullycombined for the transit through the tunnel of motor vehicles with theirengine in an inoperative condition.

As is visible from the drawing, the tunnel is made up of two'runs, eachof which is intended for travel of the vehicles in one direction,denoted by the arrows in Figure 15.

Each run is arranged in such manner as to bring about a difference inlevel between its inlet I, I', respectively and outlet O, O',respectively, the vehicles constantly running down-hill through thetunnel.

The inlets I, I' of the two sides of the tunnel are of course connectedwith the main road by sloping connections (not shown). l

Preferably, the slope is not uniform through the length of each tunnelside.

Each side is composed of a plurality of successive portions decreasingin slope 43, 44 47 and 43', 44' 47', respectively. l

Y The vehicles entering the tunnel inlet I or I' with oneway tralicfirst travel over a short launching track 43 in order to acquire aninitial speed of about 40-50 km./h. (for x motor vehicles of an averageweight of about 2, metric tons), which is maintained over the portion 44or 44 of suitable slope.

The subsequent sections 45, 46 or 45', 46' should be such in slope thatthe speed of the vehicles travelling through the tunnel is graduallyreduced to 30-35 km./ h. and 20-30 km./h. respectively.

The nal section 47 or 47 is of further reduced steepness, so that thevehicle stops at the tunnel outlet O or O'. For the sake of safety ashort up-hill section 49 can be provided at the outlet (Fig. 16).

The tunnel of the abovedescribed type is equipped with carriages andpropelling means according to this invention as previously describedwith reference to Figures l to 10.

It will be understood that for the sake of economy at lirst one sideonly for two rows of vehicles may be provided, allowing the vehicles tofreely travel downhill through the tunnel, the propelling-means beingemployed merely on the up-hill path.

The propelling means are in any case operated only when the compositionof the atmosphere and visibility within the tunnel, detected forinstance automatically by suitable means make it advisable to hold uptrafc with the engines running.

This invention may be particularly advantageous with road tunnelsresulting from the adaptation of existing railway tunnels to the tratiicof road motor vehicles.

The necessity of such adaptation may arise, for instance, upondisruption of the railway lines owing to war damage. In this case it isconvenient to utilize railway tunnels, which would otherwise remaininoperative and useless, for the traic of special military vehicles by,removing from the tunnels the rails and replacing them by a road surfaceof suitable type.

It is further convenient to equip such converted tunnels with one of thepreviously described propelling means, both for regulating traic andbecause the trafc will obviously be very great.

Two manners of carrying out road tunnels by converting railway tunnelsshall now be described with reference to Figures 17 and 18. As will beclearly seen from the drawing, the rails have been removed from thetunnel 50 and replaced by a concrete road paving 51. The road paving isinterrupted by two longitudinal slots 52, 53, respectively about 25centimeters wide, symmetrically arranged with respect to thelongitudinal middle plane of the tunnel and parallel therewith. A rail54, 55, vrespectively is anchored to the bottom of each of said slotsthrough the interposition of wood slabs 56, 57, respectively, for thesake of quick replacement. These rails form the guide for the carriages,for instance of the type shown in Figures and 6, to which are securedthe motor vehicles travelling through the tunnel in both directions.

with their engines in an inoperative condition, propelled for instanceby an electric locomotive. v

The profile of the road paving is of special shape designed to form twoilat road surfaces 58, 59 (Fig. 17) laterally confined by lateralinclined surfaces 60, 61 and 62, 63, respectively, so that the vehicleis guided on its transit through the tunnel. A further shape of theprole of the road paving is shown in Fig. 18 in which the elementscorresponding to those of Fig. 17 are denoted by the same referencenumerals.

In the construction shown in Figure 18 the grooves 52 and 53accommodating the rails 54, 55 are arranged further away from thelongitudinal central plane of the tunnel, the inclined surfaces 61, 62being eliminated to form a at central road surface 64 which may be usedfor the transit of special large-sizer vehicles, such as, for instance,trailers for transporting heavy armoured cars. In order to enhance theaction of the sloping surfaces 60 63, the latter may be lined with sheetmetal.

Of course the rails on which the carriages roll may be in the number oftwo on either side and can be arranged in auxiliary tunnels such asshown in Figures l and 2Q The propelling means can be of any suitablepreviously described type.

What I claim is:

1. In a tunnel having a road and a channel beneath the surface of theroad communicating with the surface of the road a vehicle towing systemcomprising, in combination, a plurality of movable carriages disposed insaid channel for towing the vehicles along the road, means individuallyand releasably connectable to a corresponding carriage for selectivelyconnecting and disconnecting vehicles individually to individualcarriages, means in said channel for guiding said carriages through saidchannel when the carriages are moved therethrough, means releasablyengageable with said carriage for selectively moving the individualcarriages in tandem and in spaced relationship at selected speedscollectively along said channel, said last mentioned means comprising atleast one` rotatably driven first endless-band towing means disposed insaid channel extending longitudinally therein for engaging saidcarriages to move them along said channel at a constant rate of speedand a short rotatably :driven second endless-band towing means driven ata variable rate of speed and disposed at the inlet of the tunnel foraccelerating the carriages together with the vehicles connected theretoand delivering them to said first constant speed endless band towingmeans, and non-combustion type motors operably connected to said firstand second towing means respectively to drive them independently of eachother so that the atmosphere in the tunnel is not affected by saidmotors, whereby vehicles are propelled along the surface of the roadwith their engines inoperative so as not to contaminate the atmospherein the tunnel by exhaust gases.

2. In the combination according to claim 1, in which said guiding meanscomprises a rail in the channel, said rail having a web portion and inwhich a carriage 'comprises a rotatable wheel riding on said rail, aplurality of rollers spaced from the axis of the wheel and positioned oneither side of the web said rollers slidably engaging the rail,substantially rigid connection means between the rollers and the wheel,whereby a carriage is movable on the rail and guided thereon.

3. In the combination according to claim l, in which said guiding meanscomprises two rails fixed on opposite side walls of the channel beneaththe surface of the road, each of said rails having an upper and a lowertransverse portion substantially normal to a web, means mounting therails in fixed position with the webs substantially parallel to the sidewall of the channel, and in which a carriage comprises a first frame,two pairs of rotatable wheels mounted on said frame, said wheels havinga peripheral projection on the inner side adjacent the frame so as toride on the upper transverse portion of the rails, a second frameremovably connected to said first frame and extending downwardly fromsaid first frame, a pair of spaced wheels mounted on said second frameeach of said last mentioned wheels having peripheral projections so asto ride and be guided on the lower transverse portions of the rails,whereby said carriage is movable and guided on the rails.

4. A system for towing vehicles through a tunnel having a road, whilethe vehicles bear on the road surface by means of their respectivewheels and have their engines inoperative, comprising, in combination,means comprising a plurality of like devices connectable to respectivevehicles individually for towing and guiding the vehicles collectivelythrough said tunnel in tandem, means individually connectable to saiddevices for selectively connecting and disconnecting vehiclesindividually to said towing and guiding devices, means cooperating withsaid devices to guide them along a predetermined path in Said tunnel,means releasably engageable with said de s Vf vices for moving saidtowing and guiding devices along the tunnel in said predetermined path,said moving means comprising at least one rotatably driven irst endlessband propelling means disposed extending longitudinally in a directioncorresponding with a direction in which said tunnel extends and havingmeans fixed thereon for releasably engaging said devices for propellingsaid towing and guiding devices along the tunnel in tandem at a constantspeed and a second endless band propelling means movable at a variablespeed and arranged in tandem with said rst endless band at the tunnelinlet and having means fixed thereon for releasably engaging said towingand guiding devices successively together with individual vehiclesconnected thereto to accelerate said devices until they reach theconstant speed of travel of said rst mentioned endless band propellingmeans disposed along the tunnel and for subsequently releasing saidtowing and guiding devices and delivering them with the vehiclesconnected thereto to the first propelling means successively, drivingmeans of the non-combustion type operably connected to the first andsecond propelling means for reversibly driving said rst and secondpropelling means independently of one another so that the atmosphere inthe tunnel is not affected by the driving means and the vehicles.

References Cited in the le of this patent UNITED STATES PATENTSCreighton Ian. 17, 1888 McLaughlin July 15, 1890 Dunne May 17, 1892Ashland May 15, 1906 Neebe May 5, 1908 Willson Oct. 13, 1908 McDonagh etal Dec. 15, 1908 Harling Dec. 14, 1909 Smith Sept. 10, 1912 Bates Feb.29, 1916 Hiss et al. Dec. 7, 1920 Mason Dec. 5, 1922 Hunter May 6, 1924Hewes Ian. 1, 1929 Butler Nov. 26, 1935 McCaul Dec. 16, 1952 Boyko etal. Dec. 16, 1952 Kendall et al. July 3l, 1956

